Well there is no mandate or absolute need for someone to start a blog , it is more of a personal choice to create a brand for themselves . Its just a reflection of the society and the vice-versa on to the self that can be recorded in a sensible and entertaining way by keeping the record as a public journal for the self. To cut to the chase - it's merely a show off or a facade of one's own digital imagery in the social media with a little more control on the framework.
Read if it's intriguing, comment if you have something to say (less meaner !) , talk if you must. Ignore if anything else. Peace.